Development and Implementation of Point Kinetics and Associated Models in COBRA-TF
Open Access
- Author:
- Raja, Faisal Z.
- Graduate Program:
- Nuclear Engineering
- Degree:
- Master of Science
- Document Type:
- Master Thesis
- Date of Defense:
- None
- Committee Members:
- Maria Nikolova Avramova, Thesis Advisor/Co-Advisor
Maria Nikolova Avramova, Thesis Advisor/Co-Advisor - Keywords:
- COBRA-TF
Point Kinetics
TRACE - Abstract:
- The research consists of the implementation of a power calculation model in the reactor thermal-hydraulic analysis code, COBRA-TF, using the point kinetics approach. COBRA-TF in its current form has a fixed power model (power vs. time table). With the addition of the new point kinetics model, one should expect more realistic results since it accounts for the thermal-hydraulic feedback. Along with the point kinetics model, two other associated models are developed and implemented into the code: the decay heat model, and the feedback model. In order to verify the validity and accuracy of the new model in COBRA-TF, the reactor analysis code TRACE is used for code-to-code verification. A sample test problem, which consists of a ¼ core of a Pressurized Water Reactor being modeled as nine separate channels, is used to perform code-to-code verification using a 50 % loss of coolant flow transient. Based on this sample test problem, an input deck for COBRA-TF and an identical input model for TRACE are created. Steady state comparison results show consistent agreement between the two codes with respect to pressure, coolant density, coolant temperature, and liquid velocity. Transient results, which compare similar state parameter as well as reactor power and reactor multiplication factor, however, have shown some discrepancies especially for coolant density and channel temperature. TRACE predicts a flat temperature response whereas COBRA-TF predicts an increase in temperature. Reactor power and multiplication factor do show agreement between the two codes. Both COBRA-TF and TRACE predict a decline in reactor power. Similarly, both codes predict the reactor multiplication factor to have a downward slope from an initial value of one and it stays under one at the end of the transient.